The present invention provides compounds, pharmaceutical compositions containing one or more of those compounds or their pharmaceutically acceptable salts, which are effective in inhibiting the binding or function of various chemokines to chemokine receptors. As antagonists or modulators of chemokine receptors, the compounds and compositions have utility in treating various immune disorder conditions and diseases.
Chemokines, also known as chemotactic cytokines, are a group of small molecular-weight proteins that are released by a wide variety of cells and have a variety of biological activities. Chemokines attract various types of cells of the immune system, such as macrophages, T cells, eosinophils, basophils and neutrophils, and cause them to migrate from the blood to various lymphoid and none-lymphoid tissues. They mediate infiltration of inflammatory cells to sites of inflammation, and are responsible for the initiation and perpetuation of many inflammation diseases (reviewed in Schall, Cytokine, 3:165-183 (1991), Schall et al., Curr. Opin. Immunol., 6:865-873 (1994)).
In addition to stimulating chemotaxis, chemokines can induce other changes in responsive cells, including changes in cell shape, granule exocytosis, integrin up-regulation, formation of bioactive lipids (e.g., leukotrienes), respiratory burst associated with leukocyte activation, cell proliferation, resistance to induction of apoptosis and angiogenesis. Thus, chemokines are early triggers of the inflammatory response, causing inflammatory mediator release, chemotaxis and extravasation to sites of infection or inflammation. They are also stimulators of a multitude of cellular processes that bear important physiological functions as well as pathological consequences.
Chemokines exert their effects by activating chemokine receptors expressed by responsive cells. Chemokine receptors are a class of G-protein coupled receptors, also known as seven-transmembrane receptors, found on the surface of a wide variety of cell types such as leukocytes, endothelial cells, smooth muscle cells and tumor cells.
Chemokines and chemokine receptors are expressed by intrinsic renal cells and infiltrating cells during renal inflammation (Segerer et al., J. Am. Soc. Nephrol., 11:152-76 (2000); Morii et al., J. Diabetes Complications, 17:11-5 (2003); Lloyd et al. J. Exp. Med., 185:1371-80 (1997); Gonzalez-Cuadrado et al. Clin. Exp. Immunol., 106:518-22 (1996); Eddy & Giachelli, Kidney Int., 47:1546-57 (1995); Diamond et al., Am. J. Physiol., 266:F926-33 (1994)).
T lymphocyte (T cell) infiltration into the small intestine and colon has been linked to the pathogenesis of Coeliac diseases, food allergies, rheumatoid arthritis, human inflammatory bowel diseases (IBD) which include Crohn's disease and ulcerative colitis. Blocking trafficking of relevant T cell populations to the intestine can lead to an effective approach to treat human IBD. More recently, chemokine receptor 9 (CCR9) has been noted to be expressed on gut-homing T cells in peripheral blood, elevated in patients with small bowel inflammation such as Crohn's disease and celiac disease. The only CCR9 ligand identified to date, TECK (thymus-expressed chemokine) is expressed in the small intestine and the ligand receptor pair is now thought to play a pivotal role in the development of IBD. In particular, this pair mediates the migration of disease causing T cells to the intestine. See for example, Zaballos et al., J. Immunol., 162(10):5671-5675 (1999); Kunkel et al., J. Exp. Med., 192(5):761-768 (2000); Papadakis et al., J. Immunol., 165(9):5069-5076 (2000); Papadakis et al., Gastroenterology, 121(2):246-254 (2001); Campbell et al., J. Exp. Med., 195(1):135-141 (2002); Wurbel et al., Blood, 98(9):2626-2632 (2001); and Uehara et al., J. Immunol, 168(6):2811-2819 (2002); Rivera-Nieves et al., Gastroenterology, 2006 November; 131(5):1518-29; and Kontoyiannis et al., J. Exp. Med., Vol. 196, Number 12, Dec. 16, 2002. In addition CCR9 bearing lymphocytes have been show to mediate the pathology of filariasis (lymphatic filarial disease) and inhibition of CCR9 has been correlated with reduction of the pathology associated with such conditions. See for example Babu et al., Journal of Infectious Diseases, 191: 1018-26, 2005.
The identification of compounds that modulate the function of CCR9 represents an attractive new family of therapeutic agents for the treatment of inflammatory and other conditions and diseases associated with CCR9 activation, such as inflammatory bowel disease.
PCT Published Application WO 2003/099773 (Millennium Pharmaceuticals, Inc.) discloses compounds which can bind to CCR9 receptors of the formula

PCT Published Application WO 2005/004810 (Merck & Co., Inc.) discloses brandykinin B1 antagonists or inverse agonists of the formula

PCT Published Application WO 2005/113513 (ChemoCentryx, Inc.) discloses compounds that modulate various chemokine receptors.